Light induced off-flavour formation is a well known problem in the beverage and food industry. A variety of off-flavour generating reactions that are initiated or accelerated by exposure to light have been described in the scientific literature. The rate at which these off-flavour generating reactions progress is usually increased dramatically by exposure to light with a wavelength below 500 nm, particularly UV-light.
Light sensitive flavour changes in beverages and foodstuffs may be inhibited effectively by packaging these beverages or foodstuffs in a material that will not transmit light frequencies that promote off-flavour generating reactions. However, for a variety of reasons it is sometimes desirable to employ a packaging material that does not exhibit this light shielding quality. In those cases, the composition of the beverage or foodstuff will need to be optimised to achieve sufficient stability against light induced flavour changes. Where this cannot be achieved with the usual constituents of such beverages or foodstuffs, special light stabilising additives may be used.
It is known in the art to employ a large variety of additives for the stabilisation of beverages and food products against light induced off-flavour formation. Many of these additives derive their effectiveness from their capability to inhibit off-flavour generating reactions, e.g. by scavenging of one or more of the reactants and/or key intermediates. In addition, additives have been proposed that scavenge the off-flavour causing reaction products (e.g. by forming a non-volatile complex) or that promote degradation of these reaction products to less odorous products.
Instead of minimising the impact of light induced off-flavour generating reactions as described above, it is also possible to prevent these reactions from occurring by introducing an additive that neutralises the undesired impact of said light and particularly the ultraviolet component of said light. U.S. Pat. No. 5,948,458 describes a method for the prevention of spoilage, rancidity or off-color in a liquid food product containing unsaturated lipids and fats caused by exposure of the liquid food product to ultraviolet light comprising the step of adding to said food product an ultraviolet absorbing effective amount of tricalcium phosphate.
U.S. Pat. No. 4,389,421 teaches the addition of organic compounds containing 1,8-epoxy groups, such as 1,8-cineole, to prevent or significantly reduce light struck flavour in malt beverages. It is hypothesised therein that the addition of 1,8-epoxy compounds to malt beverages prevents the formation of methyl butenyl mercaptan by preventing cleavage of a five carbon fragment (iso-pentenyl chain) from the iso-hexenoyl side chain of iso-α-acids, which fragments would otherwise react with the sulfhydryl group forming the iso-pentenyl mercaptan (methyl butenyl mercaptan). It is stated that the 1,8-epoxy compounds may prevent formation of methyl butenyl mercaptan by reacting with the iso-pentenyl fragment or by protecting the iso-hexenoyl side chain from fragmenting or by blocking the sulfhydryl group from reacting with the iso-pentenyl fragment.
Many food additives that have been proposed for stabilising beverages or foodstuffs against light induced off-flavour formation have to be labelled as chemical or artificial entities on the product package. With a view to consumer acceptance manufacturers of beverages and foodstuffs generally do not like to use such chemical additives but, instead, prefer to employ additives that make more appealing ingredient labels (consumer-friendly labels) possible and that deliver similar functionality.